With both wheels off the ground, turn one wheel, if the other wheel turns the same direction, it is either welded or a sure grip. The best way to tell is to remove the rear cover and look to see if the gears are welded, or if there is a SG unit in there. There are two types of SG units, the "clutch" type, and the "cone" type. The clutch type is much better for the 7 1/4, as it uses 4 spider gears, where the cone type only uses two spider gears.
PS: the 7 1/4 SG units are the same as those used in the other Mopar rears, only smaller.